• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.649-656
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• 2012

The Global Positioning System (GPS) is widely utilized for commercial and military applications to estimate the location of the user or object. The GPS suffers from various intentional or unintentional interferers and it requires estimating the accurate angle-of-arrival (AOA) of the GPS signal to suppress interference signals and to efficiently detect GPS data. Since the power of GPS signal is very low comparing with the noise and interference signals, it is extremely difficult to estimate GPS AOA before despreading. Although AOA of GPS signal is usually estimated after despreading, it requires choosing the GPS AOA among results of AOA estimation because they include AOAs of interference and GPS signals when existing high-power interferers. In this paper, we propose the efficient choosing algorithm of the GPS signal among the estimated AOAs. The proposed algorithm compares the estimated results before despreading and after despreading for choosing AOA of GPS signal. Computer simulation examples are presented to illustrate the performance of the proposed algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.983-995
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• 2004

This paper introduces a pre-compensation filter for compensating dispersive and resonant properties experienced along the usage of non-ideal wideband antennas in impulse communication systems. It has been well blown that the transmitted impulse signal becomes deformed because of dispersive and resonant characteristics. Accordingly, in spite of using ideal template signal at the correlator in coherent receiver, these impairments degrade overall performance attributed to low level of coherence. To overcome this problem this paper exploits a realization technique of pre-compensation filter purposely installed at transmitter whose stability is automatically guaranteed because it has an inversion form of minimum-phase ARMA (Auto-Regressive Moving Average) system. The performance of proposed scheme will be shown in results from computer simulations to verify its affirmative impact on impulse communication system with regarding several distinctively shaped antennas.

• Water for future
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• v.12 no.1
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• pp.56-59
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• 1979

A prompt subsurface runoff producing mechanism whih creaters a depletion curve of direct runoff hydrograph is simulated by a dead zone dispersion model technique. Runoff processes are carried out by routing of the outflow resulted from previous linear channel and effective rainfall from its corresponding subwatershed through a series of conceptual linear channels representing subwatersheds of a catchment. Working rules are explained for evaluation the model parameters such as translatory velocity, diffusive factor, and parameters concerning the infiltration and relative magnitude of the prompt subsurface flow region.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.3
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• pp.232-239
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• 1993

In this paper the effect of wave motion acting on the natural folds of dispersed material in the coastal zone is studied. After integrating the usual diffusion equation with respect to the depth using shallow-water approximation simpler equation for integrated concentration was obtained. which holds for long waves of arbitrary amplitude and far any arbitrary barotropic flows. Different situations of long wave action on impurity concentration in the frame of this equation are considered.

• KAPE Magazine
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• s.176
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• pp.4-5
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• 2011

정부가 구제역 발생 이후의 대한민국 축산업 재건을 위해 대대적인 리모델링 착수에 들어갔다. 방향은 ${\blacktriangle}$방역메뉴얼 개편 ${\blacktriangle}$조직정비 ${\blacktriangle}$축산업 선진화 등 크게 3가지이다. 이와 함께 정부는 지난 3월 24일부로 구제역이 진정돼 안정적인 통제가 가능하다는 판단에 따라 구제역 경보단계를 '심각'에서 '경계'로 한 단계 낮추기로 했다. 구제역 발생에 따른 위기 경보 단계는 '관심(주변국 발생)${\rightarrow}$주의(국내 발생)${\rightarrow}$경계(확산)${\rightarrow}$심각(3개 시 도)' 등 총 4단계로 구성돼 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.150-154
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• 1998

CDMAPCS 시스템은 Rake 수신기를 이용만 경로 다이버시티를 채택하여 우수한 시스템 향상을 얻을 수 있어 주로 TDMA 시스템에서 적용하고 있는 등화기를 사용할 필요가 없다. 그러나 CDMA PCS 시스템의 역방향 링크에서는 순방향과는 달리 채널의 크기 및 위상 추정에 필요한 파이롯 채널이 없어 성능의 저하를 가져오게 된다. 따라서 역방향 링크에서 채널환경에 따라 Rake 수신기의 성능에 미치는 영향을 분석하는 것은 중요하다. 본 논문에서는 시스템 성능 및 광대역 채널 파라미터 분석을 위해 광범위한 라이브러리와 시스템 구성의 유연성을 가지고 있는 Ptolemy [1] 플랫폼에서 CDMA PCS 시스템의 역방향 링크 규격에 따라 각 블록을 사용자 정의로 구현하였다. Ptolemy 시뮬레이터를 이용하여 CDMA PCS 시스템의 역방향 링크 비트오율 성능을 채널의 특성과 연관지어 분석하였다. 그리고 가상할 수 있는 각 채널 모델을 이용하여 CDMA PCS 시스템의 성능과 광대역 채널 파라미터 (예: 지연확산)와의 상관 관계를 파악하였다. 본 연구에서 CDMA PCS 시스템에서는 일반적으로 알려져 있는 지연확산보다 평균지연 파라미터가 더 높은 상관 관계가 있음을 발견하였다.

• 농업기술회보
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• v.51 no.6
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• pp.14-15
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• 2014

구제역과 조류인플루엔자 등 악성전염병의 발생 후 방역조치는 매우 힘들고 어려우며 국가적으로 많은 손실을 유발하기 때문에 각 농장마다 차단방역 조치를 철저히 실시해 질병의 발생 및 확산을 막아야 한다. 겨울철 주의해야 할 가축질병의 관리기술에 대해 알아보자.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.30-36
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• 1999

Jamming is an important factor in the military satellite communication system. In this paper, link capacity and jamming margin of the DS-CDMA(Direct Sequence-Code Division Multiple Access) military satellite communication system are analyzed and calculated under a multitone jamming. The analysis was performed with two types of transponders loaded on a geosynchronous satellite. Calculation methods for link capacity and jamming margin were obtained. The results of the analysis show that capacity of a transponder which does modulation/demodulation, decoding/encoding in addition to despreading/respeading is twice as much as that of a tranponder which does despreading /respreading only.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.3
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• pp.124-132
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• 2009

The optimal type and discharging position of ocean outfall of wastewater have been determined by hydrodynamic modeling, near-field dilution modeling, and far-field dispersion modeling. Tide and tidal currents have been simulated by a finite element hydrodynamic model showing good agreements with field observations. Based on the hydrodynamic simulation results candidates of ocean outfall position were preliminary determined. Submerged single port and submerged multi-port diffuser were selected as discharging system alternatives and finally designed by considering tide, tidal currents and water depth. Initial dilution of wastewater discharged from the designed ports has been estimated by CORMIX system. A 2-dimensional random-walk dispersion model has been employed to simulate far-field dispersion of discharged wastewater.

• The Magazine of the IEIE
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• v.21 no.7
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• pp.43-51
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• 1994

본 논문에서는 최근 주목을 받고 있는 대역확산 통신방식을 이용한 무선LAN 시스템의 하드웨어 구현에 관해 논한다. 내용으로는 직접확산 (Direct Sequence Spread Spectrum (DS/SS)) 통신방식을 이용한 무선 LAN 전송부 구조, 디지탈 정합필터를 이용한 역확산 및 비동기 DS/SS 수신기 구조, DBPSK 및 DQPSK 변복조 방식, Timing 및 Clock 복원, 그리고 Carrier Sensing 방식등이 포함된다. 또한 실제 시스템 구현을 위해 필요한 몇가지 변수들에 대해서도 논한다.